HTTPfy

Port 2733 (signet-ctf)

IANA assigns port 2733 to signet-ctf: Signet CTF.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
signet-ctf TCP Signet CTF Greg Broiles -
signet-ctf UDP Signet CTF Greg Broiles -

Check what is listening on port 2733

Linux: is anything listening on TCP 2733?
sudo ss -tlnp 'sport = :2733'
Linux: UDP 2733
sudo ss -ulnp 'sport = :2733'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2733
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2733 '
Windows (Command Prompt)
netstat -ano | findstr :2733
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2733 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2733
From Windows
Test-NetConnection HOST -Port 2733
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2733

Block port 2733 in the firewall

ufw
sudo ufw deny 2733/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2733 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2733 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2733' -Direction Inbound -Protocol TCP -LocalPort 2733 -Action Block
ufw
sudo ufw deny 2733/udp
iptables
sudo iptables -A INPUT -p udp --dport 2733 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2733 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2733' -Direction Inbound -Protocol UDP -LocalPort 2733 -Action Block

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2731fyre-messanger2732g5m2734ccs-software2735netiq-mc

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.